Lets be straight forward, the drug war is only nominally a war on narcotics; it should instead be seen as a low-level counterinsurgency (COIN) against anti-capitalist elements. One look at the drug war statistics show that it has not succeeded at its publicaly stated aim. For example the U.S. still remains a very large drug consumption market with any reductions re-balanced by the continuing growth of the global consumption market. A global market that continues to be supplied by the main producing nations like Colombia, cocaine, and Afghanistan, heroin; two nations with a strong U.S. military pressence.
But in terms of the state being able to criminalise anti-capitalist elements it has no competitor. Mexico, for example, has a long history of leveraging anti-drug operations to criminalise activists starting with the U.S. promoted Operation Condor in the late 1970s.
Neoliberal development and the War on Drugs
In terms of the development, the drug war can assist capital in various ways as it creates an environment where anti-development activists can be illegally suppressed. First it allows the state to criminalise activists as narcos on little or no evidence. The presence of narco groups in the countryside also pacifies activists by making it dangerous to protest due to ongoing conflicts between groups. Activist can be assassinated by state/corporate interests with responsibility appointed to the narcos. The list goes on, but briefly the insecurity of the drug war creates an environment that obscures and facilitates the criminality and violence of neoliberal development as it removes barriers to capital accumulation.